The goal of this project is to study the repetitive firing properties of neurons with defined roles in the generation of behavior. The three types of repetitive firing characteristics to be examined are: adaptation, rebound excitation, and burst generation. We will examine these mechanisms with four questions in mind: 1) What is the ionic mechanism for each process? 2) Are differences in repetitive firing properties between cells due to qualitative differences, i.e., presence of a particular channel type? Alternatively, are quantitative differences, such as channel density or channel kinetics, more important? When channel kinetics vary between two cell types, is there a general variation affecting several different channel types? 3) How are repetitive firing characteristics modulated by synaptic transmitters? 4) How do the repetitive firing characteristics of a particular cell contribute to shaping the behavior controlled by that cell? We will use whole cell voltage clamp and patch clamp techniques to study these problems in identified neurons in the abdominal ganglion of Aplysia. A complete description of the ionic mechanisms that determine different aspects of the repetitive firing characteristics of neurons is essential for a complete understanding of the normal physiology and the pathophysiology of the nervous system.